This is a study to determine methods for the preservation of corneal tissue suitable for penetrating keratoplasty. Previous studies on this grant enabled us to develop a method of long term preservation by storing isolated corneas in liquid nitrogen. Since the majority of corneas were being used between 4 to 7 days after preservation we sought a method which would not be technically as difficult as cryopreservation and would provide adequate storage for up to 7 days after death of the donor. Storage of corneas in a modified tissue culture medium, M-K medium, has proven to be successful in this respect. Present studies are aimed at finding exactly how the M-K medium accomplishes this protection and whether other storage media would provide better protection. The study also includes work on the clinical specular microscope. Because it is now possible to see individual corneal endothelial cells and see many changes not apparent with the slit lamp it is possible to make better evaluations of the effects of different types of surgery and also to initiate steroid therapy earlier in cases of corneal graft rejection. BIBLIOGRAPHIC REFERENCES: Bigar, F., McCarey, B.E. and Kaufman, H.E.: Improved corneal storage: Penetrating keratoplasties in rabbits. Exp. Eye Res. 20:219, 1975. Binder, P.S., Abel, R., Polack, F.M. and Kaufman, H. E.: Keratoplasty wound separations. Amer. J. Ophth. 80:109, 1975.